Recent events in Ferguson have started a nationwide conversation about police body cameras. Supporters say they can give clear evidence of what happens at scenes where officers are involved.

In Celina, Texas, a routine call turned into a police officer tackling a man to the ground in his driveway.

It's possible to think the police officer used excessive force, by looking at the dashboard camera. When you take a look at what happened just seconds before, from the vantage point of the body camera, you can see the suspect take a swing at the officer before he's finally subdued.